I just had to check them out on the net, they are amazing and what a really cool gift. For all those crafty people out there, I think they would be relatively easy to make as well. You wouldn't be limited to the theme either. You could do a "Kitchen Tea" one for the new bride, or "House warming", you are only limited by your imagination - instead of using diapers, use hand towels or tea towels, oh God I am giving myself a head ache, I'm having imagination overload LOL.
Here are a couple of pictures I found. These were borrowed from an American site, but there are lots of Australian sites, where you can order them if you don't have the crafty minded brain to make one yourself.
Oh and if you did want to have a go at making one yourself, there are lots of sites that offer instructions for how to do it yourself for free. I think they are neat.